Dynamo.



E. TORMIN.

' DYNAMO.

APPLIGATION HLKBD MAR.3.1911.

Patented Aug. 18, 1914,

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E. M. TORMIN.

DYNAMO.

LPPLIGATION FILED MAR.3,1911.

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'UNTTED sTATns PATENT clarion.

EGMONT MAX TORMIN, OF NEWTON CENTER, MASSACHUSETTS, ASSIGNOR TO HOLTZER- CABOT ELECTRIC COMPANY, OF BROOKLINE, MASSACHUSETTS.

DYNAMO.

Specification of Letters Patent. Patented Aug, 18, 1914,

Application led March 3, 1911. Serial No. 512,140.

lTo all whom it 'may concern.'

Be it known that I, EcMoN'r M. ToRMiN, a subject. of the Emperor of Germany, and a resident of Newton Center, in the county of Middlesex and State of Massachusetts, have invented .a new and useful Improvement in Dynamos, of which the following is a specification.

My invention relates to dynamo electric machines and its object is to produce a direct current machine that can be shortcircuited with impunity, and to provide the various improvements hereinafter more fully set forth.

One embodiment of my machine is illustrated in the drawings which Vaccompany and form a part of this specification.

In the drawings', Figure 1 is a diagram showing one arrangement of circuits that may be employed in connection with my improved dynamo. F ig.2 is a horizontallongi.- tudinal section. Fig. 3 is a longitudinal vertical section taken on the line 3-3 of Fig. 2. v

ln the drawings selected for more fully disclosing my invention, 1 is a casing of aluminum or other suitable material. One ond of the casing is provided with a cover plate 3. A cap 4 secured to said plate by the screw l and the pin rl,'or in any other suitable manner, may be employed to complete the inclosurc of the dynamo.

Cast integral with the plate is the housing 5 for the bearing 6, herein shown as a ball bearing. The casing' is provided with a housing 7 for the other bearing 8, and the shat't 9 which carries the armature 10 and conmiutator l1 is arranged to rotate in the bearings 6, 8.

12 represents the laminated core of the field magnet consisting of very soft iron disks, which in the present instance are shown as riveted together by the rivets 12 and held in the casing by a driving fit. The ieldcore is provided with suitable windings, shown in the present ,instance as two series windings 1l and two shunt windings 13.

The torwawily-extending arms 17, 18, and the brush-holders 19, 19, each,provided with an integral flange 19, are secured to the housing 3 and are suitably insulated trom each other and from. the other metallic parts of the machine.

The screws 20, 20 electrically and me- 23, and the end of said insulating plate pro.-

jects through the bifurcated end of the arm 18 to connect with the spring 26 secured as shown to said arm 18. The contact points 24; on the switch and-25 on the arm 18 are normally separated by the head 27 coperating with the button 23. The pin 27 located in the bore at the forward. end of the shaft 9 is normally held in the position shown in Fig. 1 by the4 arms 29which are pivoted at 29 to the collar 28, the spring 30 secured to the governor weights 29\main. tainingsaid pin in its outward position.

The leads 32 to the shunt windings 13" are electrically connected to the brushes. v

Referring to the diagram shown in Fig. 1, the series windings 14 are connected through armature 10 and the shunt wind ings 13 and thence by conductor 31 to the centrifugally-governed switchv2l, and when the switch is closed,the storage battery 47, or other suitable source of energy', is connected in circuit through the conductor 31, and the contactpoints 24, 25. The spring 30 of the governoris so adjusted that when the armature arrives at a predetermined speed of rotation, the head 27 isdrawn inwardly by theaction of the governor, and the contacts 24, 25 and 21., 25 the action of the spring 26.

The shunt eld coilsare so designed and the laminated field core is so constructed and proportioned that the residual magnetism of the attcr is insuflicient at the maximum speed or rotation of the armature toV excite said field. coils to the degreer necessary to enable the machine to picleup., It follows as,- amatter of course that for any speed lower than said maximum speed, the machine will not pick-up". It will be understood that by the term maximum speed, I mean the greatest speed at which the. machine would be likely tobe driven in ordinar usage. lVhen the mach-ine is driven at spec shigher than .that which I term the maximum closed by speed, tue machine may or may not ipicl up but it will be understood that such speeds are but rarely attained.

Inasmuch as the particular machine specifically described herein is designed for motor vehicles, it will be understood that its speed will vary between wide limits.

It is of course well understood that it is not new to provide direct current generators with laminated field cores and that such generators will pick-up at definite speeds,

although at much lower speeds they will not t pick-up but in the present invention the field coils are s designed and the laminated field core .isl so constructed and proportioned that for the highest speed at which the "machine in ordinary usage is likely to be driven, the residual magnetism will not cause *it to""pick up As soon as a deinite speed hasA been reached and the contacts at 24, 25 closed, the source of energy 47 is connected in circuit with the field windings and the machine at once proceeds to generate current. The direction of' current flow from the source 47, which preferably is a storage two currents through the shunt coils is the same and that of' the flow through the series coils 1s opposite. As soon the coils are energized by the source 4:7, the potential dethe generator become short-circuited across the leads to the battery e7, it will be obvious that the excitation of the machine will drop .to practically zero, and the electromotive force developed across the brushes will be negligible.

Inasmuch as there is not suiiicient residual ma netism in the iield to enable the machine to pick-up, no precautions are necessary.

in connecting the battery to the dynamo. For example, in the present case the right hand brush is positive because it is connected to the positive pole of the battery, but if the battery were reversed, said right hand brush would become negative. ln other Words, the polarity of the source governs the polarity of the dynamo, because the voltage impressed by 'the armature at and below maximum speed on the fiel d magnet, due to the residual magnetism of the field core is less than the voltage impressed upon said magnet by the battery.

inasmuch as the Edison battery above referred to cannot be injured by owf'charg i or over-discharging, or complete L battery protectingdevices are not e8, 4S represent lamps connected allel with the external circuit of the gris, ator and also with the storage battery 4:7. ln an automobile they would represent, for ex" ample, the side lights. It Will be understood, however, that my generator is not limited to use with motor vehicles. As soon as the speed of rotation falls below that which is necessary to close the contacts Q4, 25, the external load, such as the lamps 48, 48 are supplied entirely by the source 47.

A convenient means of driving the generator when used on automobiles is shown in Fig. 2. The clutch members 40, faced with rawhide el, or other suitable friction material, are slidably mounted on the shaft'9 and prevented from having rotational movement relative thereto by the spline 50. Each of the barrels l2 is provided with a plurality of pins 43 and spiral springs 44;. One set of pins cooperates with the collar 39 and the other set with the collar 4:5, secured to the shaft by the Cotter pinAC. The rim of the fly-wheel i9 of an engine may be held in frictional engagement with the clutch members, the degree of engagement therewith being determined by the springs 44.

It will be understood that while I have described one embodiment of my invention with some particularity, nevertheless various modifications may be made by those skilled in the art, both in the apparatus described and in the circuit arrangements employed therewithywithout departing from the' principle of my invention.

' l claim:

A direct current dynamo electric machine having a 'field magnet provided with a laminated coreso constructed and proportioned with respect vto the field coil that at the maximum speed of rotation the residual magnetism of said core'will be insuiiicient to cause said machine to pick up, an armature, anda source of electrical energy electrically connected with the armature and field magnet, the voltage impressed by the armature at maximum speed on said field magnet due to the residual magnetism of the field core being less than the voltage impressed upon said field magnet by said source of electrical energy.

ln testimony whereof', l have hereunto subscribed my name this lst day of March, flQll.

EGMONT MAX TORMIL Wfitnesses r Gro. K. Woonwonrrn B. ToaruNsoN. 

